Transfering files using Secure Copy (scp)
OpenSSH is useful for securely running shell commands on remote systems. The Secure Copy command, scp, which is part of the OpenSSH suite, copies ﬁles from a remote system to the local system or from the local system to a remote system. The command uses the SSH server for authentication and encrypts data when it is being transferred.
You can specify a remote location for the source or destination of the ﬁles you are copying. The format of the remote location should be in the form [user@]host:/path. The user@ portion of the argument is optional. If it is missing, your current local username will be used. When you run the command, your scp client will authenticate to the remote SSH server just like ssh, using key-based authentication or prompting you for your password.
The following example demonstrates how to copy the local /etc/yum.conf and /etc/hosts ﬁles on host, to the remoteuser’s home directory on the remotehost remote system:
[user@host ~]$ scp /etc/yum.conf /etc/hosts remoteuser@remotehost:/home/remoteuser remoteuser@remotehost's password: password yum.conf 100% 813 0.8KB/s 00:00 hosts 100% 227 0.2KB/s 00:00
You can also copy a ﬁle in the other direction, from a remote system to the local ﬁle system. In this example, the ﬁle /etc/hostname on remotehost is copyed to the local directory /home/user. The scp command authenticates to remotehost as the user remoteuser.
[user@host ~]$ scp remoteuser@remotehost:/etc/hostname /home/user remoteuser@remotehost's password: password hostname 100% 22 0.0KB/s 00:00
To copy a whole directory tree recursively, use the -r option. In the following example, the remote directory /var/log on remotehost is copied recursively to the local directory /tmp/ on host. You must connect to the remote system as root to make sure you can read all ﬁles in the remote /var/log directory.
[user@host ~]$ scp -r root@remoteuser:/var/log /tmp root@remotehost's password: password ...output omitted...
Transfering files Secure File Transfer Program (sftp)
To interactively upload or download ﬁles from a SSH server, use the Secure File Transfer Program, sftp. A session with the sftp command uses the secure authentication mechanism and encrypted data transfer to and from the SSH server.
Just like the scp command, the sftp command uses [user@]host to identify the target system and user name. If you do not specify a user, the command will attempt to log in using your local user name as the remote user name. You will then be presented with an sftp> prompt.
[user@host ~]$ sftp remoteuser@remotehost remoteuser@remotehost's password: password Connected to remotehost. sftp>
The interactive sftp session accepts various commands that work the same way on the remote ﬁle system as they do in the local ﬁle system, such as ls, cd, mkdir, rmdir, and pwd. The put command uploads a ﬁle to the remote system. The get command downloads a ﬁle from the remote system. The exit command exits the sftp session.
To upload the /etc/hosts ﬁle on the local system to the newly created directory /home/ remoteuser/hostbackup on remotehost. The sftp session always assumes that the put command is followed by a ﬁle on the local ﬁle system and starts in the connecting user’s home directory; in this case, /home/remoteuser:
sftp> mkdir hostbackup sftp> cd hostbackup sftp> put /etc/hosts Uploading /etc/hosts to /home/remoteuser/hostbackup/hosts /etc/hosts 100% 227 0.2KB/s 00:00 sftp>
To download /etc/yum.conf from the remote host to the current directory on the local system, execute the command get /etc/yum.conf and exit the sftp session with the exit command.
sftp> get /etc/yum.conf Fetching /etc/yum.conf to yum.conf /etc/yum.conf 100% 813 0.8KB/s 00:00 sftp> exit [user@host ~]$